Hi! I have looked at some used and some new keyoards, but it`s difficult to deceide what to get/what I need. E.g.I can get a used Yamaha PSR-550 or a Yamaha PSR-E423 for about the same prize. Some tell me that the older PSR-550 have better sound than the new PSR-E423? Both have probably much more functionality than I need.. Mostly I want to use it to learn to play a little bit, and to record and arrange for my little daughter who is learning to play the clarinet.